Here at Frugal Mechanic, we deal with a lot of data on a daily basis.    We have parts that fit hundreds of different makes (e.g. Audi),  lots of different years (e.g 2002 Audi),  thousands of different models (e.g. 2002 Audi A4) and a bunch of different Engines (e.g. 2002 Audi A4 1.8T).

When you combine those numbers with the number of categories (e.g. Oil Filter) and unique parts (Bosch 72211),  you get some really really big numbers.   Try 245,304,018 total combinations (e.g. 2002 Audi A4 1.8T Bosch 72211 Oil Filter).

Just to put that in perspective...that means almost every single person in the US could have their own unique engine/part combination (the US population is currently around 300 million).   That's a lot of parts!